fix: bulletproof first-boot container creation and install reliability

Remove the Bitcoin RPC 60-second gate that blocked 13+ dependent containers
(mempool, electrumx, btcpay, lnd, fedimint) from being created on first boot.
Containers now always get created and auto-restart via health monitor once
Bitcoin becomes responsive — the designed recovery path.

Additional hardening:
- Validate archy-net creation with retry (silent failure broke DNS)
- Verify critical images are loaded, re-load from tarballs if missing
- Create SearXNG settings.yml before container start (was missing)
- Run reconciler automatically after first-boot failures
- Add load-images as explicit systemd dependency with 900s timeout
- Propagate config write errors in install.rs (bitcoin.conf, lnd.conf)
- FileBrowser password change: retry loop (6 attempts) + 0o600 perms
- Post-start verification: detect containers that exit immediately
- Add 2s dependency waits between container starts

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

image-recipe/build-auto-installer-iso.sh

@@ -1368,12 +1368,14 @@ FBUNBUNDLED
     cat > "$WORK_DIR/archipelago-first-boot-containers.service" <<'FBCSERVICE'
 [Unit]
 Description=Create core Archipelago containers on first boot
-After=archipelago-setup-tor.service network-online.target podman.service
+After=archipelago-load-images.service archipelago-setup-tor.service network-online.target podman.service
+Wants=archipelago-load-images.service
 ConditionPathExists=/opt/archipelago/scripts/first-boot-containers.sh
 ConditionPathExists=!/var/lib/archipelago/.first-boot-containers-done
 
 [Service]
 Type=oneshot
+TimeoutStartSec=900
 ExecStart=/opt/archipelago/scripts/first-boot-containers.sh
 ExecStartPost=/usr/bin/touch /var/lib/archipelago/.first-boot-containers-done
 RemainAfterExit=yes
@@ -1395,12 +1397,14 @@ else
         cat > "$WORK_DIR/archipelago-first-boot-containers.service" <<'FBCSERVICE'
 [Unit]
 Description=Create core Archipelago containers on first boot
-After=archipelago-setup-tor.service network-online.target podman.service
+After=archipelago-load-images.service archipelago-setup-tor.service network-online.target podman.service
+Wants=archipelago-load-images.service
 ConditionPathExists=/opt/archipelago/scripts/first-boot-containers.sh
 ConditionPathExists=!/var/lib/archipelago/.first-boot-containers-done
 
 [Service]
 Type=oneshot
+TimeoutStartSec=900
 ExecStart=/opt/archipelago/scripts/first-boot-containers.sh
 ExecStartPost=/usr/bin/touch /var/lib/archipelago/.first-boot-containers-done
 RemainAfterExit=yes